Systemic lupus was once considered a fatal disease in young women, but patient mortality and morbidi have significantly improved in the last decade. As women with lupus approach a normal life expectancy, they are at risk for low bone mineral density (BMD). The precise frequency of low BMD in Caucasian and African-American women with SLE is unknown, although preliminary evidence has documented an increased frequency of low BMD and fractures in Caucasian women with lupus. The reasons for low BMD in lupus patients are unclear. Little is known on BMD or fractures in African-American women with lupus despite the fact that this racial group is afflicted by lupus three to four times as often as Caucasian women. Although corticosteroids may play a role, there is evidence that they may not be as important as other disease factors or alteration of traditional osteoporosis risk factor consequent to diagnosis and treatment. The overall goals of this project are to conduct both a cross-sectional study and a longitudinal study to determine the effect of lupus on low BMD and the rate of bone loss in 256 women with lupus and 256 close friend healthy controls matched for age, gender, race, and menopause status. BMD at the hip and lumbar spine and all risk factors will be measured at study entry and after two years of follow-up. Risk factors to be studied include: 1) traditional osteoporosis risk factors that may be affected by the consequences of the disease and/or its treatment (reproductive history, menstrual and menopause status, use of oral contraceptives and/or hormone replacement therapy, physical activity, and vitamin D levels); 2) disease specific risk factors (disease activity, disease severity, and renal disease); and 3) treatment related risk factors (corticosteroids and anticonvulsants). Data will be analyzed using t- tests, classification and regression trees (CART), and correlation and multiple regression analyses. This study will contribute to work done by other investigators by; examining the relationship between BMD and potentially reversible or preventable risk factors for low BMD. This information will direct the development of intervention strategies to prevent low BMD and subsequent fracture in these high risk patients.